I know many graduate students that buy homes during their stay in Pittsburgh rather than renting, and simply sell when they leave. Often, those homes end up in the hands of other graduate students.

I mean I am about to do this (in Cleveland at CWRU instead of Pittsburg at CMU) but the principle of the thing is the same. These cities have some of the lowest costs of living to be found anywhere in the US. I would also note that Cleveland has the same problems mentioned in the article to a degree, but is managing to retain bio-tech firms. This is mainly due to the top notch institutions (hello Cleveland Clinic) which are in the city.

True, but remember that most startup founders are not just graduating college.